• Each node must have at least one interface connected to the network.
  • Each interface must have an address provided.
  • Each host needs a unique hostname set.
    • This also includes a unique mac address.
    • Especially if VMs are created from existing ones (useful point this one).
  • Some ports need to be opened as well.
    • Used by the various ports.
  • For example on a Master Node:
    • Interface –> eth0
    • Address –> 192.168.1.10
    • Hostname –> master-01
    • Contains the following: kubectl, kube-api, kubelet, kube-scheduler, kube-controller-manager, etcd
    • Accepts connections on port 6443 on the kube-api server.
    • The kubelet listens on port 10250.
    • The kube-scheduler listens on port 10259
    • The kube-controller-manager listens on port 10257
    • The etcd server listens on port 2379.
  • For example on the Worker Node:
    • Interface –> eth0
    • Address –> 192.168.1.11
    • Hostname –> worker-01
    • The kubelet listens on port 10250
    • Exposes services for external access on ports30000-32767
  • If you have multiple Master nodes, these ports need to be opened as well:
    • Need port 2380 opened on all of the Master Nodes, so that the etcd clients can talk to each other.
  • Can check required port ranges here: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#check-required-ports
    • Good place to check if things aren’t working.
  • Useful netstat command: 
    netstat -plnt

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